The value of lock-up shares to become eligible for trade will shrink by about 40 billion yuan (6.2 billion U.S. dollars) from March to nearly 143.6 billion yuan in April.
Nearly 11.1 billion shares from 85 companies will become tradable on the Shanghai and Shenzhen stock exchanges in April, according to market information provider Wind.
Less supply of new tradable shares means lower downward pressure on the market, which is very sensitive following repeated slumps in previous months.
Huaxia Bank will see the unlocking of some 2.9 billion non-tradable shares on April 26, the largest volume to be released this month.
Under China's market rules, major shareholders of non-tradable stocks are subject to one or two years of lock-up before they are permitted to trade the shares.